WASHINGTON (Reuters) - Frequent breakdowns of advanced uranium enrichment devices have inadvertently helped Iran comply with restrictions in the international agreement curbing its nuclear programme, according to a new report by a Washington-based think tank.

FILE PHOTO - An Iranian national flag flutters during the opening ceremony of the 16th International Oil, Gas & Petrochemical Exhibition (IOGPE) in Tehran April 15, 2011. I REUTERS/STR

Iranian compliance also is due to tougher policing by U.S. President Donald Trump’s administration of the 2015 pact to prevent Tehran from developing nuclear weapons, the Institute for Science and International Security said in a report due on Friday. A copy of the report was seen by Reuters.

“Iran can be expected to continue to push the deal’s limits, commit violations and seek interpretations that are unfounded,” the report said. “One should expect many struggles to keep Iran within the nuclear limits for the duration of the deal.”

For those reasons and because Tehran is unlikely ever to build a financially viable uranium enrichment plant, an expansion of Iran’s programme would either be a “colossal waste of money ... or the basis of a nuclear weapons programme, which would not care about costs,” the report said.

Washington and its negotiating partners in the agreement should find a way to make the deal’s restrictions permanent or “severely” extend their expiration times, it said.

Under the deal between Iran, Britain, China, France, Germany, Russia and the United States, Tehran agreed to restrict its nuclear programme in return for the lifting of economic sanctions that had crippled its economy.

The report comes as Trump weighs whether to certify to Congress that Iran is complying with the agreement. He has until Oct. 16 to make that decision.

Decertifying Iran could lead Congress to reimpose U.S. sanctions on Iran, threatening to collapse the deal and intensify tension in the Middle East.

Supporters of the deal, called the Joint Comprehensive Plan of Action, insist that strong international monitoring will prevent Iran from developing nuclear bombs. Iran has denied that it is seeking nuclear weapons.

The International Atomic Energy Agency, which monitors the pact, has found no “material breaches” by Iran, a judgement with which Washington has concurred.

Tehran has exceeded some deal restrictions, such as a limit on its heavy water stockpile, used in nuclear reactors, the Institute for Science and International Security said in a November 2016 report. But it either rectified some infractions or won exemptions - while President Barack Obama was in office - before the pact took effect in January 2016.

In its new report the institute listed other alleged Iran compliance issues, including changes to the design of a heavy water reactor that can produce plutonium, another weapons fuel.

BREAKING CENTRIFUGES

Iran’s improved compliance this year in part has been “unintentional or accidental” because advanced uranium enrichment devices called centrifuges have broken during testing more often than expected, according to the think tank report.

Enrichment produces low-enriched uranium for power plants, but it also can make highly enriched weapons-grade uranium.

By August, Iran had tested eight advanced IR-8 centrifuges although the deal limits it to one at most, the report said, adding that Iran also operated between 13 and 15 interconnected IR-6 machines, which the deal restricts to 10.

However, according to the report, all but one of the IR-8s and many of the IR-6s broke because carbon fibre components failed.

David Albright, a former U.N. nuclear inspector who authored the new report, said Iran’s compliance also had improved because the United States is taking a tougher line on attempts to “violate the nuclear limits and exploit loopholes.”

Two sources, including a senior U.S. official, said on Wednesday that the White House does not want to kill the deal.

Instead, it wants lawmakers to hold off taking action while it discusses with European allies making the limits on Iran’s programme permanent and fixing what U.S. officials consider other flaws, said the sources, who requested anonymity.